Mandel’s decision came in an open letter to friends and family and leaves Cleveland banker Mike Gibbons for now as the leading Republican candidate. Brown, who defeated Mandel in 2012, is seeking a third term in a swing state race likely to be crucial to Democratic hopes of regaining a Senate majority in November’s elections.

Mandel stated in his letter that his wife, Ilana, has a health issue that will require him being there for her and their three children. He calls the decision “difficult … but it’s the right one.” He didn’t offer details on her condition, but wrote: “Understanding and dealing with this issue is more important to me than any political campaign.”

A message seeking comment was left Friday for Mandel.

Although he initially endorsed Florida Sen. Marco Rubio in last year’s Republican presidential primaries, irritating supporters of Ohio Gov. John Kasich, Mandel has since become a supporter of President Donald Trump. Trump carried Ohio handily in 2016, and Mandel has echoed him on policies such as immigration.

Mandel was the front-runner for the GOP nomination but had his critics. Last month, the Franklin County Republican Party endorsed Gibbons, a political novice, over Mandel.

In a statement, Gibbons said he’s sending prayers for the Mandel family and hoping for the best.

Gibbons also called on Republicans to unite behind him to defeat Brown, although Mandel’s departure could lure other Republicans into the race.

“As a conservative outsider, no one is better positioned to end career-politician Sherrod Brown’s career than I am,” Gibbons said.

There’s still a month left before the filing deadline for the May 8 primary.

Ohio Republican Party Chairwoman Jane Timken praised Mandel for making “an honorable decision to be with his family in a time of need” and offered thoughts and prayers.

“Our focus is, and will continue to be, on electing Republicans statewide and continuing to make Ohio stronger,” Timken said in a statement.

U.S. Rep. Pat Tiberi was among Ohio Republicans who had considered running in the Senate race before deciding against it. A Tiberi spokesman, Rob Nichols, said Friday that Tiberi is continuing with his earlier announced plans to leave Congress later this month to take the top position at the Ohio Business Roundtable business policy group in Columbus.

Kasich is term-limited from seeking a third term as governor this year, but a Kasich strategist, John Weaver, said in a Tweet on Friday that Kasich had “bigger fish to fry.” A steadfast critic of Trump, Kasich could run for president again in 2020.

Mandel, 40, said he will finish his second term as treasurer. A former legislator and Marine veteran of the Iraq war, he was re-elected in 2014.

In his letter, Mandel expressed confidence he had been “on the path to defeating” Brown and had a better “voice and perspective.” But he also expressed respect for Brown, “for having the passion to advocate for his beliefs.”

Brown spokesman Justin Barasky issued a statement wishing Mandel, his wife and family the best and hopes for a speedy recovery for Ilana.

Brown, 65, won election to his second term in 2012 with nearly 51 percent of the vote to nearly 45 percent for Mandel. Brown was also considered a potential running mate for Hillary Clinton in 2016, before she chose Virginia Sen. Tim Kaine.

Brown unseated Republican Mike DeWine in 2006. DeWine is now Ohio’s attorney general and is running for governor.